If you are experiencing continuous redirects with “/wp-admin/&reauth=1″ in the address bar then it could be that the “install.php” file still resides in:
/wp-admin/install.php
- Backup install.php
- Rename/Move/Delete install.php
- Empty the browser cache and history – in Firefox CTRL+SHIFT+DELETE
- Restart the browser
- Attempt to login and it should let you in straight away!